Metal forming tools used in superplastic forming (SPF) and quick plastic forming (QPF) typically include a first portion that defines a gas pressure chamber and a second portion that defines a forming surface. During operation of an SPF or QPF forming tool, a metal blank is placed between the first and second portions of the forming tool such that a first side of the blank is in fluid communication with the chamber and a second side of the blank faces the forming surface. Fluid pressure is introduced into the chamber, which acts on the first side of the metal blank, causing the blank to deform so that the second side contacts, and assumes the shape of, the forming surface.
The tool is heated so that the metal blank is maintained at a temperature sufficient for plastic deformation at the forming pressure, typically between 825° F. and 950° F. It is therefore desirable for the tool to be configured for minimal heat transfer to the surrounding environment in order to minimize the amount of energy required to maintain the tool at the desired temperature and the costs associated therewith. Accordingly, the prior art teaches thermally efficient forming tools to reduce heat loss to the environment.
Maintenance of prior art tools must often be performed after several hundred forming cycles. Such maintenance may include removing aluminum buildup on critical forming surfaces. However, prior art tools often take a significant amount of time to cool from their elevated operating temperatures of greater than 800° F. to a temperature suitable for maintenance, such as less than 110° F. For example, some prior art tools require approximately eighteen hours to cool to a sufficiently low temperature for maintenance, during which time the tool is unproductive.